1. Field of the Invention
The invention relates to analytical test devices which use immunochromatographic assays formulated on a competitive immunochemical protocol, and which determine small hapten, non-protein molecules such as those representing the presence of drugs of abuse. More particularly, the invention relates to self-contained analytical devices which require only the addition of a few drops of body fluid such as urine or other liquid to initiate a complex, multi-step immunoassay that produces a visually perceptible precipitin via antigen/antibody reactions, and which do not require instrumentation or sophisticated training to assess the results. The invention further relates to housing articles useful for packaging kits for these immunoassays, to novel reagents, and to methods for utilizing the novel reagents in the test devices which simultaneously can assay in a single device for up to five (5) of the National Institute of Drug Abuse (NIDA) designated drugs of abuse recommended in a drug screen.
2. Prior Art
The measurement of physiologically important substances in urine, serum and tissue with immunological principles is an important recent development in immunology (V. P. Butler, Pharmocol. Reviews (1978), 29, 103-184). In particular, drug-specific antibodies and antigens have been used in the development of a variety of immunological assay procedures for the detection and/or quantification of antibodies or antigens in the bodily fluids of humans and animals. Immunoassay methods have distinct advantages when compared, for example, with techniques using thin layer chromatography, gas chromatography, gas chromatography/mass spectroscopy or high performance liquid chromatography because of the high specific accuracy associated with immunoassays and their ease of use.
Most immunological testing procedures are focused upon the antigen-antibody reaction or competition which provides an end point with an insoluble or agglutinated precipitate (E. A. Kabat, Methods in Enzymology, Vol. 70 (1980), Academic Press, New York, pp. 3-49). Existing non-isotopic immunoassay test kits are based on enzyme-linked immunosorbent assay (ELISA), homogeneous enzyme multipled immunoassay techniques (EMIT), latex agglutination assays and fluorescent polarization immunoassay. More recently, membrane-based particle immunoassays have been reported for human pregnancy tests which measure the level of human chorionic gonadotropin (HCG) (UK Patent Application, GB 2,204,398A, Apr. 26, 1988). These assay procedures generally have the disadvantage of requiring multi-step protocols, multiple reagents, reagent storage problems, and the need of special designed instrumentation or specially trained personnel to assess and record the test results. Specific immunoassays using reagent-impregnated test strips and latex particles have been reported in U.S. Pat. Nos. 3,857,931; 4,094,647; 4,690,907; and 4,740,468; G.B. Patent 1,589,234; European patents 0,225,054; 0,138,442; and 0,136,799; and in G.B. Patent Application 2,204,398A (Unilever).
There is a need for a test and/or device which is simple to use and which can be used anywhere rather than only in a laboratory setting, which via competition of the analyte, or drug, and the analyte conjugate for limited antibody binding sites, can identify presence or absence of drugs of abuse in humans, and which does not require instrumentation to read the end results. The test devices of this invention will detect drugs of abuse, for example, in a stable immunoassay configuration using certain novel protein conjugates of these drugs of abuse, and the accompanying antibodies. There is also a need for a self-contained analytical testing device which can simultaneously perform assays for multiple drugs of abuse in a single device.